Irregularities in early development of the sperm, egg or embryo can lead to an imbalance of chromosome number in the developing embryo (i.e. missing or extra chromosomes). This chromosome imbalance can lead to implantation failure, miscarriage, or the birth of an affected child.

What is the test for?
Following In Vitro Fertilization, the healthiest looking embryos are selected for transfer to the patient, assessed by morphological appearance (ie: cell number and quality) and developmental rate.  However, this gives no information about the genetic makeup of the embryo.  Irregularities in early development of the sperm, egg or embryo can lead to an imbalance of chromosome number in the developing embryo (i.e. missing or extra chromosomes).  This chromosome imbalance can lead to implantation failure, miscarriage, or the birth of an affected child.
Studies have shown that some couples have an increased risk of producing embryos with chromosome imbalance (eg: where the female partner is 37 years or older or with a history of recurrent miscarriage).  Biopsy of a cell from the developing embryo can enable testing to identify the status of chromosomes commonly involved in such imbalance.  Embryos with no abnormalities for the chromosomes being tested, and therefore possessing greater potential for developing to term, can then be selected for transfer.

How is this done?
Embryo biopsy is performed on Day 3 after egg collection.  Embryos that have developed to at least 5 cells are suitable for biopsy.  A hole is drilled in the zona (the outer shell) of the embryo and 1 or 2 cells are removed from the embryo (Figure 1).

Figure 1: Embryo Culture and Biopsy

The biopsied cells are tested using a technique called Fluorescent In Situ Hybridisation (FISH), which screens for the nine chromosomes most frequently involved in imbalance (ie: chromosomes 13, 15, 16, 17, 18, 21, 22, X and Y).  The embryo is kept in culture whilst the testing of the biopsied cells proceeds.  Fluorescent dyes are used to tag specific chromosomes and these show as "dots" corresponding to the number of chromosomes present in the biopsied cell (Figure 2).  Testing takes approximately 8 hours to complete.  Embryos identified as having no imbalance for the chromosomes tested can then be transferred on Day 4 or Day 5.  When a number of embryos with no chromosome imbalance are identified, morphological criteria are also used to determine those best for transfer.  Surplus embryos with no chromosome imbalance which are not transferred but which continue to develop satisfactorily to the blastocyst stage are frozen.  Chromosomally abnormal embryos are discarded or donated to research.

Figure 2: FISH Analysis of biopsied cell/s

What are the costs?
Information relating to the cost of embryo biopsy and chromosome testing is available from Monash IVF.  Please note that additional costs will be incurred for IVF services.  Please contact Monash IVF for a list of current prices.

What else do I need to know?

• Embryo biopsy has been applied extensively at Monash IVF and other major IVF clinics throughout the world and does not appear to have adverse affect on the embryo's potential to implant or develop into a pregnancy. 
• It may not be possible to obtain a FISH result from some or all of the biopsied embryos.  Some embryos may not be of sufficient quality to biopsy, or in some embryos the test results may not be conclusive. 
• Embryo biopsy with chromosome testing is appropriate as an embryo selection process if more than 2 embryos are suitable for biopsy on Day 3.  Embryo biopsy is an invasive procedure that may not be considered advisable with only a small number of embryos.  If there are only 2 embryos on Day 3, it may therefore be considered more beneficial to transfer these embryos without biopsy.
• Technical limitations of the test suggest an error rate of approximately 10%. 
• This test is not a diagnostic test because it cannot provide an absolute guarantee of the chromosome status of the embryo from the analysis of only one cell.  In some embryos, one cell may not be representative of the whole embryo. 
• This screening test involves only 9 chromosomes (ie: X, Y, 13, 15, 16, 17, 18, 21 and 22).  Thus, abnormalities involving other chromosomes cannot be excluded. 

Prenatal diagnosis is always recommended in an ensuing pregnancy.

Quality Systems
Monash IVF employs a very high standard of quality assurance. The laboratories are NATA accredited.  Through the application of quality systems we monitor and provide standards of excellence in quality service, care and advice.